Harrows are well known farm instruments used for working and leveling the ground, and may be attached to and pulled by a plow or other cultivating implement. Alternatively, they may simply be attached to a tool bar and pulled through a previously tilled field.
A very commercially successful harrow is disclosed in U. S. Pat. No. 3,991,831 to Foster. That harrow includes an elongated leveling rod having a series of angled teeth which are urged into the ground in order to break up and pulverize clods and smaller chunks of earth into loose soil. The leveling rod is attached to the lower ends of mounting arms which are adapted to be connected to the tool bar or to the rear beam of the leading implement.
While the harrow of the Foster patent functions well in plowed and relatively loose ground, it is less satisfactory when used to level minimally tilled soil. Trash and residue left from the previous year's harvest tend to build up between and in front of the teeth, and prevent the teeth from breaking through the crust and leveling the soil.
To address these shortcomings, Phillip Foster (inventor of the harrow of the '831 patent) invented an improved leveling harrow having angled teeth carried on a rotatably supported rod. Rotation of the rod keeps residue from accumulating between the teeth and thus improves performance of the leveling harrow. This improved harrow is more fully described in commonly assigned U.S. patent application Ser. No. 08/261,391, filed on Jun. 17, 1994. As described therein, the angled teeth are disposed on segments that are telescoped nonrotatably over the elongated rod, which in turn is journaled by laterally spaced bearings supported by mounting arms. An advantage of the toothed segments is that variable length leveling rods are readily fabricated by telescoping more or fewer toothed segments on the rod.
While the leveling harrow disclosed in the '391 application provides an effective solution to the prior art problems discussed therein, other improvements are desired. More specifically, it has been found that installation of the elongated rod onto the ground working implement is sometimes exceedingly time consuming, particularly with longer rod lengths. The rod is installed by aligning it with the laterally spaced bearings and inserting it therethrough (installing the toothed segments therewith). Press fitting bearings along the length of the long rod, particularly if it is not completely straight, can present substantial difficulty. It has been found that, for various reasons including variations in mechanical tolerances, perfect alignment of the rod and bearings is not achieved. As a result, the rod often binds within the bearings, making installation of the rod more difficult and time consuming.